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Neil, before any of that additive stuff, try running it on Shell V-power (Nitro or whatever else they're calling it this week) in and see if it makes a difference.

 

Mike

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Neil, I think the given timing figure was correct for 5 star fuel in the 70th, but today it's not valid anymore. You might start retarding the ignition step by step and see what it gives.

In fact combustion occurs before the piston reaches the top point. :wacko:

 

If you don't use a rolling road it's a question of trial and error.

Someone might call me wrong ;)

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Need more info. PI or carbs? when does it pink? has it started in this hot weather, was OK before?

IMO boosters are last ditch - mixture and spark first.

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The original fuel requirement for a CP PI engine was 100/101 octane leaded . . . . 98/99 octane unleaded will not cut the mustard on the original timing, so amend the timing accordingly.

 

Bear in mind that distributor wear may be playing a part too, in which case it's one for Dissie Doc !

 

Cheers

 

Alec

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Not the nicest stuff to deal with, tetraethyl lead in any sort of concentration requires to be treated with the utmost respect. H&S isn't exactly one of my great concerns, but there are a few exceptions - and I wouldn't be playing with TEL without gloves suit and mask, thanks a bunch.

 

At a cost of 25p/litre or thereabouts, it's not a cheap solution either on top of £1.45/lt for super unleaded. £1.70/lt in total . . . . .

 

Damn sight easier to tweak the dissie . . . . or use NF octane booster, which is one of the few such products that actually works, albeit you need rather more than the listed dosage. Not particularly nice stuff to have around either, but not in the TEL league.

 

Cheers

 

Alec

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A lot of pinking is down to slack dizzy springs allowing too much low speed advance. It may be worth checking the "eyes" of the springs are a snug fit on the posts of the advance mechanism.

Then gradually retard until the pinking stops.

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For what its worth, I think a few degrees retarded is a better option than using nasty chemicals. To be honest, if it is only a few degrees it won't make a jot of difference in performance to normal use anyway and will be kinder to an engine that maybe a little tired. I'm also not convinced that there is a need to worry about using lead replacement and unleaded fuels either in average mileages.

Steve

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Moss do a pack of stronger springs for the centrifugal advance. Cheaper than a can of booster and very effective. Start with the first two thicker than what you have now and increase if necessary . Worked well for me on the 4 pot but I am sure the Dist Doc would do even better.

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